The present invention relates to the extruded reclosable bag making art, and is more particularly concerned with a new and improved method and apparatus for extruding bag making material having fastener profiles and alignment ribs, and the product made thereby.
Herertofore it has been proposed to provide in association with the male profile of extruded plastic zipper, so called supporting rails, as exemplified in U.S. Pat. No. 3,198,228 for assisting in the function of the zipper. To similar effect European Patent Application 0 114 373, published August 1, 1984, provide ribs in association with the plastic zipper male profile to afford controlled desired stiffening and wide-track feel in the fastener element.
In the copending Hugues and Ausnit U.S. application Ser. No. 866,917, filed May 27, 1986, now U.S. Pat. No. 4,672,723 issued June 16, 1987, and assigned to the same assignee as the present application, ribs have been provided in spaced adjacent relation to the male profile, not only for providing stiffening and wide-track feel in the male profile, but also for effectively guiding the male and female profiles into interlocked relation when pressing them together. It is to effect certain improvements in the method and apparatus for producing the male zipper profile and associated ribs, and the resulting product, that the present invention is directed, as will be apparent in the following description.
Attention is also directed to U.S. Patent Re. 27,174, which discloses providing extruded reclosable bags with rib and groove elements formed of different materials, that is extruded plastic material having desired different characteristics such as differential stiffness relative to the plastic sheet or film material.
Further of general interest is U.K. patent application GB 2 046 660 A, published November 19, 1980, and which relates to the extrusion of plastic closure strip separate from the plastic film, but with the profile and the base of the profile extruded through separately controlled channels to union of the profile and base of the profiles at a common extrusion die orifice. It is indicated that different plastic material can be used for the profile and base portions.
U.S. Pat. No. 3,841,816 discloses an apparatus for extruding tubing for fastener bags and wherein means are provided for controlling the profiles with respect to the extruded tube.